The present invention relates to chainguards for chain-and-sprocket driven vehicles and, more particularly, to chainguards for bicycles having a pedal-driven front drive sprocket and a rear driven sprocket.
Most bicycles, and many other pedal-driven vehicles, are of the type in which the user pedals a forward-mounted crank to rotate a drive sprocket linked by a chain to a driven sprocket mounted to the rear wheel of the vehicle. Many of these vehicles include some type of chainguard which encloses at least the portion of the loop of chain extending about the drive sprocket and to the driven sprocket to prevent foreign material from contacting the chain.
For bicycles, these chainguards typically are made of thin gauge metal and are attached at a rearward end thereof to the bicycle frame adjacent the rear driven sprocket, and at a forward end thereof to a bracket or brackets which may be welded to one or more of the down tube, crank housing, or seatmast of the bicycle frame. The chainguard includes mounting holes which are positioned in registry with holes formed in the mounting brackets welded to the bicycle frame, and the forward end of the chainguard is attached to the frame by bolts which are either threaded into the holes or are retained thereto by nuts.
A disadvantage of such a design is that such chainguards are limited in application only to those bicycle frames having mounting brackets with holes which correspond to the mounting holes of the chainguard. Another disadvantage is that the cost of fabricating the bicycle frames is increased by the expense of the labor and materials needed to attach or otherwise form mounting brackets on the bicycle frame. Since such mounting brackets are not movable once attached to the frame, should the brackets, or the frame members to which they are attached, be slightly out of tolerance, the bicycle frame will not accept an intended chainguard. Additional labor and expense would be required to reposition the brackets or frame members.
Accordingly, there is a need for a bicycle chainguard which is relatively inexpensive to fabricate and install and can be mounted to a relatively wide variety of frame sizes and styles. There is also a need for a chainguard which does not require the use of fixed mounting brackets to be attached to a bicycle frame. Furthermore, there is a need for a chainguard which can be mounted to a bicycle frame having one or more frame members which are slightly out of tolerance from the desired frame shape without necessitating the reworking or refabrication of the frame, chainguard, or mounting bracket.